Mixed hydrophilic/hydrophobic fiber media for liquid-liquid coalescence

ABSTRACT

An immiscible lipophilic or hydrophilic liquid phase is separated respectively from a continuous hydrophilic or a lipophilic phase liquid. Fibers having hydrophilic and hydrophobic properties are formed into a filter. The separation mechanism involves coalescence of the small droplets into larger droplets as the immiscible liquid flows through the fiber filter, and release of the large immiscible droplets from the filter. With respect to separation of a hydrophilic immiscible fluid in a lipophilic continuous fluid, the hydrophobic fibers cause small water droplets to migrate towards the hydrophilic fibers whereby large droplets are formed on hydrophilic surface. The large droplets coalescence until they are so large that they are released and drained off of the filter. The filter media can be designed by mixing hydrophilic and hydrophobic fibers in various proportions to achieve an optimum wettability range for separation of the immiscible liquid from the continuous phase liquid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of, and claims thebenefit and priority date of, U.S. patent application Ser. No.12/655,823, filed Jan. 7, 2010, now U.S. Pat. No. 8,409,448, whichclaims the benefit and priority of U.S. provisional application61/144,226, filed Jan. 13, 2009, which are both hereby fullyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the wettability of an immiscible liquid(e.g. emulsion) such as water in a continuous phase liquid such as oilutilizing a filter that has significant influence on the water removalefficiency. Wettability is an important parameter in designing suchfilter media. The wettability of the filter media is mainly governed bysurface properties of fiber material and porosity of filter. The surfaceproperties of filter can be expressed in terms of hydrophilic orhydrophobic nature of the filter. The wettability of the filter can becharacterized using the concept of Lipophilic to Hydrophilic ratio (L/H)by using a modified Washburn equation that is based on capillary risephenomena. Oil and water are used as reference liquids in thewettability characterization. In liquid-liquid coalescence filtration,separation efficiency depends on various factors including facevelocity, fiber structures, fiber geometry, fiber orientations, etc.,and also wettability of filter especially when interfacial tensionbetween liquid phases is low. The hydrophilic and hydrophobic fibersused in the filter capture the immiscible liquid and form drops on thehydrophilic material that stay on the fiber surface for extended periodsof time. Fibers having varying hydrophilic and hydrophobic propertiescan be mixed into filter media, so that the hydrophobic fibers will aidin drop migration towards the hydrophilic fibers and the formation oflarge drops on the hydrophilic surface. Large drops are desired forcoalescence and drainage.

The hydrophilic/hydrophobic filters can be utilized in the petrochemicalindustry as well as for fuels for vehicles including automobiles,planes, trains, and ships.

BACKGROUND OF THE INVENTION

In recent years, separation of water-in-oil emulsions has becomeindustrially important. Water present in liquid fuels can combine withchemicals in fuels, such as sulfur, to form corrosive compounds whichcan damage sensitive engine parts. Corrosion is a major cause ofreduction of engine life and efficiency. In addition, surfactantspresent in liquid fuels lower the interfacial tension between water andfuel and the problem of separation becomes more insidious. This can alsocause a product to be off-specification due to haze and color [1, 2].The water is present in fuels as primary emulsions with drop sizesgreater than 100 μm and as secondary emulsions with drop sizes less than100 μm. The separation of primary emulsions is often accomplished bygravity settling or mechanical means. However, coalescence filtrationusing fibrous filters is an efficient and economical way to separatesecondary dispersions.

The coalescence process occurs in three main steps. First, the fibrousbed captures water droplets. Second, the collected water phase migratesthrough the bed and coalesces. Third, the enlarged droplets are releasedfrom the fiber surfaces [3]. Coalescer performance is generallycharacterized by separation efficiency and pressure drop. The separationefficiency is highly dependent on the characteristic properties of thedispersions (e.g. composition, density, viscosity drop size) and thefiber bed (material, diameter, surface structure, porosity) [4]. Flowrate is an important factor in water-in-oil dispersion flow, as itcontrols the capture mechanism and capture probability of droplets andthe distribution of the dispersed phase. [3].

Shin [3] shows that wettability of the surface has effect on dropattachment on silane coated glass rods. It is known that criticalsurface tension of a solid to the liquid surface tension determines thecharacter of solid wettability [5]. Wettability of filter medium can berepresented by its hydrophobic or hydrophilic behavior. Moorthy [6]performed the coalescence experiments with surface functionalized filtermedia and showed that intermediate wettability gives better performance.

Research results and common experience in industry show that coalescingfilters work best with an intermediate wettability. If the medium is toowetting it tends to load up with liquid drops which restricts the airflow and results in an undesired high pressure drop. If the medium istoo non-wetting the droplets captured on the fibers quickly move alongthe fibers or leave the fibers before they have a chance to coalesce andhence the separation is not efficient.

Common practice to control the wettability is by selecting a materialfrom which the fibers are made that has an intermediate wettability, orby applying a coating, such as silanes, that gives the surface of thefiber structures the intermediate wettability. The difficulty here isfinding the right material or coating that has the best wettability fora given application. This approach does not allow for incrementalchanges in wettability.

The above-noted references as well as others are as follows:

-   1. Lloyd A. Spielman et al., “A review of progress in the    coalescence of liquid-liquid suspension and a new theoretical    framework for Coalescence by porous media are presented” Industrial    and Engineering Chemistry, Vol. 62, No. 10, 10-24 Oct. 1970.-   2. Improve suspended water removal from fuels: A better    understanding of molecular forces enhances free water separator    selection R. L. Brown, Jr., et al., Pall Corp., East Hills, N.Y.    from Hydrocarbon Processing®, December 1993.-   3. C. Shin and G. G. Chase “The effect of wettability on drop    attachment to glass rods”, Journal of Fluid Particle Separation,    Vol. 16, No. 1, 1-7, 2004.-   4. Hauke Speth., et al., “Coalescence of secondary dispersions in    fiber beds”, Separation and Purification Technology, Vol. 29,    113-119, 2002.-   5. Secerov Sokolovic, et al., “Effect of the Nature of Different    Polymeric Fibers on Steady-State Bed Coalescence of an Oil-in-Water    Emulsion”, Industrial & Engineering Chemistry Research Vol. 43 (20),    6490-6495, 2004.-   6. K. Moorthy, et. al., “Effect of Wettability on liquid-liquid    coalescence”, AFS Conference Ann Harbor, September 2005.-   7. Erbil H. Y., et al., “Transformation of Simple surface into    super-hydrophobic surface”, Science, Vol. 299, 1377-1380, 2003.-   8. Washburn E. W, “The dynamics of capillary flow”, The American    Physical Society, VOX-V II, No. 3, 374-375.-   9. Murata Toshiaki et al., “A modified penetration rate for    measuring the wettability of Coal Powders”, Journal of Japan Oil and    Chemists Society, Vol. 32 (9), 498-502, 1983.-   10. Kondo, Hiroshi, et al., “Lipid compounds in the sediment cores    of Lake Kawahara Oike, pagasaki Prefecture, Japan], documenting its    change from brackish water to fresh water”, Daigaku Kyoikugakubu    Shizen Kagaku Kenkyu Hokoku, Vol. 49 13-25, (1993).-   11. Voyutskii et al., (1953 Voyutskii, S. S, Akl′yanova, K. A.,    Panich, R., Fodiman, N., “Mechanism of separation of disperse phase    of emulsions during filtration”, Dokl. Akad. Nauk SSSR, 91 (1953),    1155-   12. Hazlett (1969) Hazlett, R. N., “Fibrous Bed coalescence of    water”, I & EC Fundamentals, 8 (1969), 625-   13. Clayfield et al, (1984) Clayfield, E. J, Dixon, A. G, Foulds, A.    W and Miller, R. J. L, “Coalescence of secondary emulsions”, Journal    of Colloid and Interface Science, 104 (1985), 498-   14. Moses and Fg (1985) Moses, S. F. and Ng, K. M. (1985) A visual    study of the breakdown of emulsions in porous coalescers. Chem. Eng.    Sci., 40 (12): 2339-2350.-   15. Basu (1993) Basu, S, “A Study on effect of wetting on mechanism    of coalescence in a model coalescer”, Journal of Colloid and    Interface Science, 159 (1993), 68-   16. Bin Ding, et al., Conversion of an electro-sound nanofibrous    cellulose acetate mat from a super-hydrophilic to super-hydrophobic    surface. Nanotechnology 17 (2006) 4332-4339-   17. Mane R. S, et al., A simple and low temperature process for    super-hydrophilic Rutile Ti02 thin films growth, Applied Surface    Science, 253 (2006) 581-585-   18. Ren O, et al., Study on the Superhydrophilicity of the Si02-Ti02    thin films prepared by sol-gel method at room temperature, J. of    Sol-gel Science and Technology, 29 (2004) 13 1-136-   19. Guo Z, et al., Stable bio-mimetic Super-hydrophobic engineering    materials, JACS Communications 127 (2005) 15670-15671-   20. Ma Y., et al., Fabrication of super-hydrophobic film from PMMA    with intrinsic contact angle below 90′. Polymer 48 (2007) 7455-7460-   21. Van der wal P., et al., Super-hydrophobic surfaces made from    Teflon, Soft Matter 3 (2007) 426-429-   22. Feng X, et al., Reversible superhydrophobicity to    super-hydrophilicity transition of aligned ZnO nano-rod films, JACS    Communication 126 (2004) 62-63-   23. Ma M., et al., Electrospun Poly (Styrene-block-dimetylsiloxane)    block copolymer fibers exhibiting superhydrophobicity, Langmuir,    21 (2005) 5549-5554-   24. Onda T, et al., Super-water-repellent fractal surfaces,    Langmuir, Vol. 12 Number 9 (1996) 2125-2127-   25. Mohammadi R., et al., Effect of surfactants on wetting of    super-hydrophobic surfaces, Langmuir, 20 (2004) 9657-9662-   26. Zhang X., et al., A transparent and photo-patternable    super-hydrophobic film, Chem. Commun (2007) 4949-4951-   27. Tadanaga K., Morinaga J., Minami T., Formation of    superhydrophobicsuperhydrophilic pattern on flowerlike Alumina thin    film by Sol-gel method, J. of Sol-Gel Science and Technology    19 (2000) 21 1-214-   28. U.S. Pat. No. 5,102,745, granted Apr. 7, 1992 to Tatarchuk et    al.

SUMMARY OF THE INVENTION

Coalescing filters are used to remove small liquid droplets fromimmiscible liquids and also gases. The droplets are carried into thefilter by the flow of the continuous phase where the droplets collidewith fine fibers. The droplets are captured on the fibers, coalesce toform larger drops, and the larger drops migrate to the exit surface ofthe medium. The larger drops are subsequently separated from the gas asby gravity settling.

An aspect of the present invention is to develop filters that can varywith respect to the wettability values thereof by using the differentmicron sized fibers with hydrophilic and hydrophobic properties.Wettability of a liquid on a flat surface can be related to contactangle and surface tension (or surface energy). Liquids on a high surfaceenergy material have low contact angles (approaching zero) and tend tospread across the surface. Low surface energy materials have highcontact angles in the range of from about 90 to about 180 degrees.Polypropylene fibers were selected as hydrophobic fibers (contact anglewith water) ˜104°) [7] and micro glass fibers are the hydrophilic fibers(contact angle with water ˜0°) [6]. The filter media has been preparedwith different compositions of micro glass and short cut polypropylenefibers. The filter media has been also characterized for theirpermeability and porosity and effect on wettability.

Measurements of wettability of porous materials such as filter media arenot trivial. The size and shape of the pores tend to deform droplets andhence the method of measuring contact angles does not work. Washburndescribes a capillary rise method for liquid uptake in a porous mediumthat is a function of the wettability (surface energy) (Washburn E. W,“The dynamics of capillary flow”, The American Physical Society, Vol.XVII, No. 3, 374-375, 1921).

Washburn's approach results in a measure of wettability through theLipophilic/Hydrophilic Ratio (L/H). Small values of L/H indicate thesurface prefers water to oil and visa versa for large L/H values.

Mixtures of glass fibers and polypropylene fibers show that we cancontrol the L/H value by controlling the mixture composition of glassand polypropylene fibers when constructing a filter medium. FIG. 1 showsa plot of glass percentage versus L/H values.

The concept of mixing fibers of different surface properties to obtain aspecific L/H value to control the coalescence properties of the filtermedium is an important aspect of this invention.

An embodiment of the present invention relates to a process for removingan immiscible lipophilic or a hydrophilic liquid respectively from acontinuous hydrophilic or a lipophilic liquid phase, comprising thesteps of: 1) forming a filter comprising a specific weight ratio ofhydrophobic fibers to hydrophilic fibers; 2) determining an initialslope of a weight gain take-up versus time plot of the immiscible liquidby said filter; 3) determining an initial slope of weight gain take-upversus time plot of said continuous liquid by said filter; 4)calculating an L/H ratio from said initial slope of the plot of saidimmiscible liquid and of said initial slope of the plot of saidcontinuous liquid and obtaining a wettability value for each; 5) forminga plurality of filters comprising different weight ratios of saidhydrophobic fibers to said hydrophilic fibers from a range of from about90% by weight of said hydrophobic fibers to about 10% by weight, or anyportion thereof, of hydrophobic fibers with the remaining weight percentbeing said hydrophilic fibers; repeating steps 2), 3), and 4) withrespect to each weight ratio of said lipophobic fibers to saidhydrophilic fibers in step 5); plotting a wettability range from saidL/H wettability values obtained from said plurality of said differentweight ratios of said hydrophobic fibers to said hydrophilic fibers; andutilizing a filter having a wetness value within a weight range of fromabout 20% to about 80% of hydrophobic fibers to hydrophilic fibers tocoalesce said immiscible liquid phase within said continuous liquidphase.

Another embodiment of the present invention relates to a process forremoving an immiscible lipophilic or a hydrophilic liquid respectivelyfrom a continuous hydrophilic or a lipophilic liquid phase, comprisingthe steps of: forming a filter containing hydrophobic fibers andhydrophilic fibers; flowing said immiscible lipophilic liquid orhydrophilic liquid respectively in said continuous liquid phasehydrophilic liquid or lipophilic liquid through said filter andcapturing said immiscible liquid; coalescing said captured immiscibleliquid; and removing said coalesced immiscible liquid from said filter.

Yet another embodiment of the present invention relates to a filter forremoving an immiscible lipophilic liquid or a hydrophilic liquidrespectively from a continuous hydrophilic liquid phase or a continuouslipophilic liquid phase, comprising: a plurality of hydrophobic fibersand a plurality of hydrophilic fibers, said hydrophilic fibers having awetting value and said hydrophobic fibers having a different wettingvalue within a liquid system comprising the immiscible lipophilic liquidor the immiscible hydrophilic liquid and respectively the continuoushydrophilic liquid phase or the continuous lipophilic continuous liquidphase; the weight ratio amount of said hydrophobic fibers to saidhydrophilic fibers being within a range of from about 80% to about 20%by weight with the remaining weight percent being said hydrophilicfibers and said fiber weight ratio amount being an effective amount tocoalesce an immiscible liquid within a continuous liquid phase; and thefilter being capable of removing an immiscible liquid from a continuousliquid phase.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an L/H value as a function of concentration(percentage) of glass fibers. The data show that changing thecomposition changes the L/H value giving a method to control the L/Hvalue;

FIG. 2 is a diagram of a mixed fiber filter medium wherein one fibertype is represented by solid lines and the other by dashed lines. Thefibers are generally randomly distributed;

FIG. 3 is a diagram of an alternating layers of wetting and non-wettingfibers that are sandwiched together to form the filter wherein (a) thelayers lie in a plane parallel to the large surface area of the filter,(b) the layers are perpendicular to the large surface of the filter, (c)the alternating layers are in a circular pattern. The layers may also beat some intermediate angle between parallel and perpendicular to thelarge surface (not shown in the drawing);

FIG. 4 is a diagram of a weight scale set up to determine the amount oftake-up of the immiscible-continuous phase solution of the presentinvention;

FIG. 5 is a graph showing the wetting kinetics for different glass andPP fiber ratios of a filter with water as the reference liquid;

FIG. 6 is a graph showing wetting kinetics for different glass and PPfiber. ratios of a filter with Viscor oil 1487 as a reference liquid;

FIG. 7 is a graph showing initial wetting kinetics for different glassand PP fiber ratios of a filter with water as a reference liquid;

FIG. 8 is a graph showing initial wetting kinetics for different glassand PP fiber ratios of a filter with Viscor oil 1487 as a referenceliquid;

FIG. 9 is a graph showing filter permeability vs. L/H values fordifferent glass and PP fiber ratios of a filter;

FIG. 10 is a graph showing L/H values vs. filter porosity values fordifferent glass and PP fiber ratios of a filter;

FIG. 11 is a graph showing droplet penetration and pressure drop withrespect to wettability and L/H values;

FIG. 12 are images showing the wettability of water on silane coatedglass rods;

FIG. 13 is an illustration showing different water contact angles;

FIG. 14 is a flow diagram illustrating collecting immiscible wateraccording to the present invention; and

FIG. 15 is a flow diagram for preparing a filter.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The filters of the present invention can exist in many sizes, shapes andforms. The one or more hydrophobic fibers and the one or morehydrophilic fibers can generally either be mixed, or exist in separatelayers. When mixed, the hydrophilic fibers and the hydrophobic-fibertypes are blended so that within a small sample volume of the filterboth types of fibers are present such as indicated in FIG. 2. In oneembodiment a slurry of the fibers can be vacuum molded to form thefilter. Non-woven filters typically have binders (glues) to hold thefiber structure together. Binders tend to stick to one type of fiber orthe other. Being of similar chemical materials, the binders often havesurface properties similar to the fibers that they stick to which aidsin the construction of the filter and its wetting properties. Theamounts of binders blended with the fibers are generally in proportionto the amount of each fiber type. Because the fibers are well blended,when the binders glue the fibers together the two types of bindersgenerally become interlocked, forming a continuous filter mediumstructure. If one type of fiber is significantly more concentrated thanthe other then only the binder for the most concentrated fiber may beneeded. The Washburn measurement as described herein below is conductedon the constructed filter and thus takes into account the presence ofthe binders.

An alternative method to make the filter with control over the L/H ratiois by utilizing thin layers of fibers of different types. This is shownin FIG. 3. As seen in FIG. 3 a, a filter is made that has alternatinglayers of a hydrophobic fiber layer and a hydrophilic fiber layer. FIG.3 b relates to a filter wherein the layers exist perpendicular to alarge surface area of the filter. In FIG. 3 c, the filter hasalternating layers are in a circular pattern. While not shown, anembodiment very similar to FIG. 3 can exist in that a spiral layers ofan alternating hydrophobic layer and a hydrophilic layer can exist thatcommence at a center point and spiral radially outward and around thecenter point. The flow of the immiscible liquid contain in with thecontinuous phase liquid can either flow from top to bottom of FIG. 3 athrough the filter, or from end to end generally parallel form thevarious layers. While the flow can be the same with respect to thefilter of FIG. 3 b, the flow is generally perpendicular to the largesurface of the filter, i.e. from top to bottom or vise-a-versa. The sameis generally true with respect to the filter of FIG. 3 c as well as thespiral filter arrangement.

Numerous types of hydrophobic fibers can be utilized so long as they areinert to the solution or gas they are treating. Hydrophobic fibersgenerally include polymers such as polyethylene, polypropylene, nomex,polyester such as polyethylene terephthalate, halogen-containingpolymers such as Teflon and poly (vinyl chloride), various rubbersincluding natural rubber, polyisoprene, and polymers derived frombutadiene, polyurethanes, polycarbonates, and silicone polymers.Hydrophobic fibers also include various minerals such as zinc oxide, forexample zinc oxide nano-rods that are superhydrophobic, and the like.Still additional hydrophobic fibers include various fibers that containcoatings thereon such as various silanes such as(3-aminopropyltriethoxysilane) APTS,(2-carboxymethylthio)ethyltrimethylsilane) CES, and(heptadecafluoro-1,1,2,3-tetrahydrodecyl)trichlorosilane FTS.

Examples of hydrophilic fibers include various types of glassesincluding sodium glass, boron glass, phosphate glass, B-glass and thelike, various minerals such as alumina, titania, and silica, variousmetals such as aluminum and alloys thereof, various polymers such ascellulose acetate, poly(methylmethacrylate), polyethylene oxide, nylon,and the like. In general, polymers that absorb or swell with water areexamples of hydrophilic polymers.

The hydrophobic fibers are generally distinguished from the hydrophilicfibers generally with regard to their wettability, that is, theirability to hold water.

Various tests or methods can be utilized such as the contact angle ofwater located on a flat surface of the fiber composition. Contact anglesless than about 90 degrees or less and generally 20 degrees or less aregenerally considered to be hydrophilic, whereas contact angles greaterthan about 90 degrees and generally at least about 120 degrees orgreater are considered to be hydrophobic.

The one or more hydrophobic and the one or more hydrophilic fibers, ofthe present invention, independently, can have various thicknesses suchas diameters as from about 0.1 to about 500 microns, desirably fromabout 0.5 to about 50 microns, and preferably from about 1 to about 10microns. For this application the fiber diameters are generally aboutthe same so that the pore sizes are about the same throughout themedium. Depending upon the type of fiber, they can generally have smoothsurfaces or contain some pores. In general the internal pore structureaffects the fiber wettability and is characterized by its contact angleand its performance is characterized by the L/H ratio. Because we aregenerally characterizing the L/H ratio the characterization of theinternal pore structure of the fibers is not essential. It is animportant aspect of the present invention that at least one hydrophobicfiber be utilized and that at least one hydrophilic fiber be utilized.That is, the present invention is free of any filters that essentiallycontain only one type of fiber such as only one hydrophobic-type fiberand no hydrophilic fiber or only one hydrophilic-type of fiber and nohydrophilic fiber. Thus, filters that essentially contain only one typeof fiber are excluded from the present invention such as filters thatcontain small amounts of a second fiber, for exampled less than 5% byweight of a second philic fiber, for example a hydrophilic fiber, orless than about 3% by weight, or less than about 2% by weight, or noamount of a second different type of philic fiber. The reasoning is asset forth hereinabove as well as herein below that the utilization of atleast one type of hydrophilic fiber and at least one type of hydrophobicfiber has been found to yield improved and efficient results with regardto removing an immiscible phase from a continuous phase liquid solution.

An important aspect of the present invention is the determination of thewettability value of the filter per se so that proper amounts ofhydrophobic and hydrophilic fibers can be utilized that will result inefficient removal of the immiscible liquid or gas from the continuousliquid phase with low pressure drops since high pressure drops canresult in expensive pumping cost. That is, high amounts of theimmiscible fluids such as water in oil can result in high watersaturation on the hydrophilic fibers that reduces porosity andpermeability of the filter with the subsequent low porosity leading toexcessive pressure drops. An additional disadvantage of high pressure isthat high shearing forces within the filter can cause droplet breakupand re-entrainment. Also, high pressure drops result in large forcesacting on the filter (pressure drop times filter area) and can cause thefilter to collapse, deform, or loose integrity and hence render thefilter useless. On the other hand, if the filter overall is toohydrophobic, there will be little or no coalescence of the immisciblefluid; the filter may capture solid particles but it would beineffective for coalescing drops.

It has been found that traditional contact angles are not suitable foruse in the present invention because liquid drops will simultaneously bein contact with multiple fibers, fiber types, and the binder (ifpresent), all of which affect the contact angle. If the fibers are toosmall in diameter, the capillary action on the immiscible liquid will beaffected and not yield a true contact angle. Instead, a liquidpenetration approach is used to measure the contact angles of filtermedia treating the pores of the media as a bundle of uniformcapillaries. This method of the liquid penetration is based on theequilibrium capillary pressure and Washburn's equation. Washburn'sequation is based on the capillary driving force of a liquid thatpenetrates a compact vertical bed of particles with small pores and theviscous drag. However, a modified Washburn equation has been found to besuitable. The modified Washburn equation is:

$\begin{matrix}{\frac{L}{H} = \frac{S_{o}n_{o}c_{w}\rho_{w}^{2}Y_{w}}{S_{w}n_{w}c_{o}\rho_{o}^{2}Y_{o}}} & ( {{Equation}\mspace{14mu} 1} )\end{matrix}$

Wherein S_(o) is the initial weight gain take-up slope of the penetratedlipophilic fluid or liquid such as oil, S_(w) is the initial weight gaintake-up slope of the penetrated hydrophilic liquid, n_(o) is theviscosity of the lipophilic liquid whereas n_(w) is the viscosity of thehydrophilic fluid. Both c_(o) and c_(w), are the same for a filtermedium where c is a geometric constant that accounts for the effectivepore diameter and the porosity. When experiments are conducted on thesame medium with the organic and water liquids then c_(w) equals c_(o)and cancel out of the equation whereas ρ_(w) is the density of thehydrophilic liquid such as water, and ρ_(o) is the density of thelipophilic liquid such as the oil. Y_(w) is the surface tension of thehydrophilic liquid whereas the Y_(o) is the surface tension of thelipophilic liquid. In order to find the L/H ratio, the slope and hencethe amount of take-up of the lipophilic liquid and the hydrophobicliquid must be determined. One method is as follows.

Materials and Filter Media Preparation

The filter samples were made of glass fibers supplied by Hollingsworthand Vose and polypropylene fibers supplied by Minifibers Inc. The slurryof fibers with desired composition was vacuum filtered onto a fine meshscreen in a mold with a hole of inside diameter 2.54 cm. The filtersamples were dried and heated in oven for 2 hrs at 100° C. The filtersamples were prepared with varying compositions of glass topolypropylene (PP) fibers, i.e. glass: PP of 80:20, 60:40, 50:50, and40:60. The reference fluids used were Viscor oil 1487 (Rock Valley Oil &Chemical Company) and water. The Viscor oil 1487 is a calibration fluidand has similar properties to that of diesel fuel. Physical propertiesof water and Viscor oil 1487 are presented in Table 1.

TABLE 1 Physical properties of reference fluids Surface Tension DensityReference Liquid (N/m) (Kg/m³) Viscosity Viscor Oil 1487 0.0285 8320.00207 (Ns/m²) Water 0.072 998  0.001 (Ns/m²)

Wettability Technique and Approach

The setup for this work is illustrated in FIG. 4. Filters samples werecharacterized prior to wettability studies for their porosity andpermeability. The porosity of the filter samples was measured using aspecial made pycnometer. The permeability was measured using a Frazierair permeability tester. The dimensions of filter sample were measuredusing calipers.

In FIG. 4, glass tube 1 was suspended from a wooden plank that isattached to scissors stand 6 which could be raised and lowered usingadjustment screw 7. This tube had a tapered diameter which was the sameas that of filter 2. Glass beaker 3 with reference liquid 4, withtemperature maintained around 23°-25° was placed on the plate ofelectronic balance 5. A stop watch was placed in front of the electronicbalance along with a video camera facing both balance and stop watch.

The tube was descended slowly with a low speed of 1.0 mm/sec. It wascarefully done with several manual practices in order to getreproducible results. It was done with the extremity of the tube justtouching the reference liquids. The video camera and stop watch wereturned on when the filter medium touched the reference liquid to recordthe change in weight with time. The decline of the glass tube was endedand the liquid rose (penetrated) through the filter until it reached thetop of the medium, causing an increase in weight of the cylinder. Thevideo recording was stopped when liquid reached top of the filtermedium.

The decrease in weight of the reference liquid on the balance is equalto the liquid taken by the filter media. The rate of decrease in weightof reference liquids on balance was measured until the liquid reachedtop of the filter. The experimental data was obtained from the recordedvideo. The weight of liquid raised in the filter media can be obtainedfor any instant of time until the liquid reaches the top of the filter.

Once the weight gain take-up of the filter has been determined withregard to the lipophilic fluid or liquid, such as an oil, and once italso has been obtained with regard to the hydrophilic liquid such aswater, charts of the weight take-up versus time are plotted as shown inFIGS. 5 and 6. In order to obtain L/H ratio that represents awettability value for a specific weight percent of the hydrophobic fiberand the remaining hydrophilic fiber, a plot is made of the initialtake-up slope with regard to time, that is, within the first few secondsof take-up before the take-up curve flattens out. Thus, an initial slopeS_(o) is obtained with regard to the oil liquid and a slope S_(w) isobtained with regard to the hydrophilic liquid such as water as setforth in FIGS. 7 and 8. These slope values are then inserted intoequation 1 along with the other known values and a specific L/H value isobtained that is referred to as a wettability value with regard tospecific amount of hydrophobic fiber and hydrophilic fiber in thefilter. Subsequently, the same determination is made with regard toother amounts of hydrophobic fiber to hydrophilic fiber generally acrossa spectrum of possible weight combinations. For example, hydrophobicfibers to hydrophilic fibers of weight ratios of about 90% to about 10%,about 80% to about 20%, about 70% to about 30%, about 60% to about 40%,about 50% to about 50%, about 40% to about 60%, about 30% to about 70%,and about 20% to about 80%, or about 10% to about 90%; or any portionthereof can be utilized. Once the weight gain take-up has been obtainedwith regard to the additional weight ratios of hydrophilicfiber/hydrophobic fibers, and plotted against time, the initial weightgain slope is obtained and inserted into formula 1. These L/H values areinversely related to wettability values as shown in FIG. 11. The L/Hvalues are then plotted against droplet penetration values wherepenetration is defined as the concentration of uncoalesced dropletscarried out of the filter divided by the concentration of the incomingdroplets. Hence, a high penetration means that most of the incomingdroplets are unaffected (do not coalesce) and the low penetration meansthat most of the incoming droplets do coalesce. Measurement of dropletpenetration is not standardized but there are methods to make themeasurements that are common. For example, a particle counter (AccuSizer780; PSS-NIComp Particle Sizing Systems, Santa Barbara, Calif.) wasutilized to monitor particle sizes and concentrations in and out of thefilter. However, because drops can coalesce and change size in thefilter, the overall separation performance was utilized to determine theQuality Factor. This means the quality factor characterizes theperformance of both the filter and the downstream separator (settlingtank, hydrocyclone, etc.). The amount of the dispersed phase (water)entering the filter was controlled using a syringe pump. The amount ofwater separated from by the downstream separator was measured bydecanting and weighing the amount of water that was separated. Theoutlet stream can further be sent to another downstream separator suchas a settling tank and the amount of water not separated can bemeasured. The two outlet masses of water should sum to the inlet. Theratio of the mass-out/mass-in is equal to the ratio of theconcentrations (by dividing by the same volume of continuous phasefluid) hence the penetration is calculated and plotted in FIG. 11 withrespect to L/H values and generally relate to a slope that curvesdownwardly, (i.e. a negative slope) as the weight ratio of hydrophilicfibers to hydrophobic fibers increases.

Also plotted in FIG. 11 is the pressure drop of the immiscible liquidcontinuous phase liquid system through the filter with different weightratios of hydrophobic fiber to hydrophilic fiber. A curve is obtainedthat increases with increasing hydrophilic fiber ratios to hydrophobicfiber ratios inasmuch as the pressure drop increases with wettability.The combination of these two curves is given by the negative log of thepenetration divided by the pressure drop and yields an inverse “U” curveor “quality factor” curve. This quality curve yields a good indicationof a range of suitable hydrophobic to hydrophilic fiber weight ratiosthat can be utilized to obtain good extraction of the immiscible fluid aliquid from the immiscible liquid-continuous liquid phase solution andyet not obtain blocking of the filter or excessive pressure drop due tothe build up of the immiscible fluid on the immiscible fluid loving typeof fibers. Conversely, high ratios of hydrophobic fibers to hydrophilicfibers yield low pressure drops since there is no build up of water onthe hydrophobic fibers. Permeability is determined by passing gas orliquid at a known flow rate and the pressure drop is measured. Thepermeability is then calculated from Darcy's Law. Accordingly, thefilters of the present invention generally have a wettability range or aquality factor that lies within a hydrophobic fiber to hydrophilic fiberweight ratios from 20 percent to about 80 percent, desirably from about30 percent to about 70 percent and preferably from about 35 percent toabout 65 percent.

The above scenario will now be discussed with regard to a specificimmiscible liquid, i.e. water and a continuous phase oil, as well asspecific amounts of hydrophilic fibers such as glass and hydrophobicfibers such as polypropylene.

FIGS. 5 and 6 summarize some of the wetting kinetics results based oncapillary rise respectively of water and Viscor oil 1487 for the filtermedia comprising varying compositions of micro glass and polypropylenefibers. FIGS. 7 and 8 show the initial wetting kinetics results forwater and Viscor oil 1487. From these figures, the values of slopesS_(o) and S_(w), are obtained and incorporated into equation 1 tocalculate specific L/H wettability values. Smaller values of L/Hindicate that filter media is preferentially water wetting and largervalues of L/H indicate preferentially oil wetting filter media. It isnoted that, as the amount of polypropylene fibers in filter mediaincreases, the L/H value increases and that L/H values decrease withincreasing amounts of glass fibers. The glass fiber only filter has thelowest L/H value. The effect of filter permeability and porosity onwettability of the filter is analyzed in FIGS. 9 and 10 respectivelywherein permeability and porosity increase with additional polypropylenefibers in the filter as does the L/H values. Porosity can be determinedusing an air/water displacement experiment or by using a pycnometer.Suitable L/H ratios range from about 1 to about 3,000, generally fromabout 2 to about 2,000, desirably from about 2 to about 200, andpreferably from about 2 or about 5 to about 150.

Once a specific lipophobic-hydrophilic system has been analyzed withregard to removal of an immiscible component thereof, other weightratios of hydrophobic fibers to hydrophilic fiber systems can beanalyzed in the same manner as set forth above to determine what typesof hydrophobic fiber hydrophilic fiber system are the most efficient.That is, the above steps as for example set forth in FIGS. 4 through 8can be repeated and the most efficient fiber ratio used for the filter.Filters can thus be designed that have different wetting properties dueto different amounts of hydrophobic and hydrophilic fibers in filter.These filter media can be characterized by using the Modified Washburnequation and wettability can be represented in terms of a Lipophilic toHydrophilic ratio. Thus, the results obtained from the above notedprocedures are used to design a filter with optimum wettability range ofwetting properties for the separation immiscible fluids from continuousphase liquids.

For example, Table 2 sets for L/H values obtained for layers ofhydrophobic/hydrophilic fiber media such as those set forth aboveutilizing water and Viscor Oil 1487. That is, the varioushydrophobic/hydrophilic fiber systems were made containing the fiberratios as set forth in Table 2 and the L/H values calculated. For theabove-noted immiscible water-continuous oil system, a ratio of 80% byweight of glass fibers to 20% by weight of propylene fibers yielded avalue of 7.021. When tested, as set forth in Table 3, this ratio gave agood efficiency of water coalescence of 0.91 and a low pressure drop of18.34 resulting in a quality factor or 0.132 that was very good. Table 4relates to L/H values for glass fiber filters containing a binderthereon whereas Table 5 relates to L/H values for mixed (i.e. nonlayered) hydrophilic/hydrophobic fiber filters. Thus, utilizing theabove procedures, different immiscible liquid-continuous liquid phasesystems can be tested and filters designed to yield high amount of takeup of the immiscible liquid with a fairly low amount of a pressure drop.

TABLE 2 L/H values for layered hydrophilic/hydrophobic fiber mediaComposition (Glass:PP) L/H G (100) 1.830 G:PP (80:20) 7.021 G:PP (60:40)8.652 G:PP (50:50) 17.438 G:PP (40:60) 22.879 G:PP (20:80 36.981

TABLE 3 Liquid-liquid coalescence results Steady state CompositionPressure Drop Quality Factor (Glass:PP) L/H Efficiency (kPa) (kPa⁻¹)100% Glass 1.83 0.84 (±0.02) 20.39 (±3.02) 0.106 (with binder) G:PP(80:20) 7.02 0.91 (±0.02) 18.34 (±3.3)  0.132

TABLE 4 L/H values for glass fiber filters showing effect of binderComposition (Glass:PP) L/H With Binder 1.83 Binder on outside edge 1.26Without binder 1.49

TABLE 5 L/H values of mixed hydrophilic/hydrophobic fiber filtersComposition (Glass:PP) L/H Glass 1.296 G:PP (80:20) 1.984 G:PP (60:40)2.744 G:PP (50:50) 89.787 G:PP (40:60) 148.742

In summary, the above procedures of the present invention relate to theextraction of an immiscible liquid from a different continuous phaseliquid in a filter essentially by three steps; that of capture,coalescence, and removal. As the liquid system moves through the filter,small droplets of an immiscible fluid, such as water, attach and adhereto a hydrophilic fiber such as glass. Continued flow of the liquidsystem results in additional water build up on the hydrophilic fibers.That is, immiscible water is coalesced into larger droplets. Finally, adroplet size is reached such that it no longer adheres to thehydrophilic fiber due to the flow of the liquid system but detachesitself. The size of the large droplet will naturally vary with regard tothe immiscible fluid be it a hydrophilic liquid such as water orhydrophobic liquid such as oil, and the wettability of the droplet onthe hydrophilic fiber or hydrophobic fiber as the case may be. Generallysuch droplet sizes can range from about 5 to about 500 microns, anddesirably within a range of from about 20 to about 100 microns. Removalof the large water droplets can be achieved by a number of methods,generally non-mechanical, such as collection of the large droplets in agravity separator. Other collection methods include hydrocyclones,membrane separators, and absorbers. Thus, the present inventionpreferably is free of or does not utilize mechanism collection methodssuch as centrifuge, etc. Putting a coalescing filter upstream of theseother devices can help the other devices to be more efficient, smallerin size, and less expensive to operate.

With regard to the coalescence filters of the present invention, otherpreparation factors include fluid velocity, fiber structure, fibergeometry, surface properties, fluid properties, and bed length(determines the filter efficiency). Liquid-liquid coalescencewettability of the fibers is also known to have effect on filterperformance, especially when interfacial tension between phases is low.Wettability of fibers can be defined as ability of filter fibers to holdwater. Wettability also depends on surface properties of fibers andporosity of the filter.

An optional aspect of the present invention is to utilize coating agentson the fibers such as silanes for making hydrophobic surfaces. FIG. 12shows the effects of various different silanes coated on glass rods withregard to water wetting. The top row shows that untreated glass rodshave high wetting. The second row from the top shows that moderatewetting is obtained whereas the third row from the top shows that onlyfair wetting is obtained whereas the bottom row shows that drops do notreadily attach to the treated fiber and are quickly removed before acoalescence can occur.

As above noted, FIG. 11 relates to a chart that can be utilized toselect ratios of hydrophobic and hydrophilic fibers to be utilized inmaking the coalescing filters of the present invention according to theabove-noted procedures. The chart shows that at high hydrophilic fibercontent the pressure drop is generally large and that at the largehydrophobic fiber content the L/H ratio is high. Thus, in order toobtain good removal of the immiscible liquid a water wetting content inthe center portion of the wettability range is usually desired.

FIG. 13 is a diagram showing different contact angles with respect tohigh wetting, intermediate wetting, and low wetting as well as thecoalescence of small droplets on the fiber. The top row relates to highwetting wherein the water contact angle is about 0°, the middle rowrelates to intermediate wetting wherein the water contact angle is lessthan about 90° and the bottom row relates to a low wetting wherein thewater contact angle is high, i.e. above 120° C.

FIG. 14 relates to a hypothetical filter media design showing thedroplets of immiscible fluid entering a filter, being captured onvarious fibers, coalescing, and then essentially dropping out a solutionand being separated in a gravity settling tank.

Immiscible liquids include oil and water, produced water, fuels (diesel,gasoline, jet fuel) and water, Complete immiscibility is rare (somewater is found in the oil phase and some oil in the water) but for thepurposes of this patent it is sufficient that two or more distinctiveliquid phases form. Perry's handbook (R. H. Perry, D. W. Green, J. O.Maloney, Perry's Chemical Engineer's Handbook, 6th ed, McGraw-Hill, NY1984, pages 15-9 thru 15-13) a table of solvents used in liquid-liquidextraction gives an extensive list of two liquid phase systems (solventA and solvent S). These tables are hereby fully incorporated byreference. However, they are also reproduced as Table 6.

TABLE 6 Selected List of Ternary Systems Component A = feed solvent,component B = solute, and component S = extraction solvent. K1 is thedistribution coefficient in weight-fraction solute y/x for the tie lineof lowest solute concentration reported. Ordinarily, K will approachunity as the solute concentration is increased. TABLE 15-5 Selected Listof Ternary Systems Component A = feed solvent, component B = solute, andcomponent S = extraction solvent. K₁ is the distribution coefficient inweight-fraction solute y/x for the tie line of lowest soluteconcentration reported. Ordinarily, K will approach unity as the soluteconcentration is increased. Component B Component S Temp., ° C. K₁ Ref.A = cetane Benzene Aniline 25 1.290 47 n-Heptane Aniline 25 0.0784 47 A= cottonseed oil Oleic acid Propane 85 0.150 46 93.5 0.1272 46 A =cyclohexane Benzene Furfural 25 0.630 44 Benzene Nitromethane 25 0.397127 A = docosane 1,6-Diphenylhexane Furfural 45 0.950 11 80 1.100 11 1151.062 11 A = dodecane Methylnaphthalene β,β′-Iminodipropionitrile ca. 250.625 92 Methylnaphthalene β,β′-Oxydipropionitrile ca. 25 0.377 92 A =ethylbenzene Styrene Ethylene glycol 25 0.190 10 A = ethylene glycolAcetone Amyl acetate 31 1.838 86 Acetone n-Butyl acetate 31 1.940 86Acetone Cyclohexane 27 0.508 86 Acetone Ethyl acetate 31 1.850 86Acetone Ethyl butyrate 31 1.903 86 Acetone Ethyl propionate 31 2.32 86 A= furfural Trilimolein n-Heptane 30 47.5 15 50 21.4 15 70 19.5 15Triolein n-Heptane 30 95 15 50 108 15 70 41.5 15 A = glycerol EthanolBenzene 25 0.159 62 Ethanol Carbon tetrachloride 25 0.0887 63 A =n-heptane Benzene Ethylene glycol 25 0.300 50 125 0.316 50 Benzeneβ,β′-thiodipropionitrile 25 0.350 92 Benzene Triethylene glycol 25 0.35189 Cyclohexane Aniline 25 0.0815 47 Cyclohexane Benzyl alcohol 0 0.10729 15 0.267 29 Cyclohexane Dimethylformamide 20 0.1320 28 CyclohexaneFurfural 30 0.0635 78 Ethylbenzene Dipropylene glycol 25 0.329 90Ethylbenzene β,β′-Oxydipropionitrile 25 0.180 101 Ethylbenzeneβ,β′-Thiodipropionitrile 25 0.100 101 Ethylbenzcne Triethylene glycol 250.140 89 Methylcyclohexane Aniline 25 0.057 116 Toluene Aniline 0 0.57727 13 0.477 27 20 0.457 27 40 0.425 27 Toluene Benzyl alcohol 0 0.694 29Toluene Dimethylformamide 0 0.667 28 20 0.514 28 Toluene Dipropyleneglycol 25 0.331 90 Toluene Ethylene glycol 25 0.150 101 ToluenePropylene carbonate 20 0.732 39 Toluene β,β′-Thiodipropionitrile 250.150 101 Toluene Triethylene glycol 25 0.289 89 m-Xyleneβ,β′-Thiodipropionitrile 25 0.050 101 o-Xylene β,β′-Thiodipropionitrile25 0.150 101 p-Xylene β,β′-Thiodipropionitrile 25 0.030 101 A = n-hexaneBenzene Ethylenediamine 20 4.14 23 A = nco-hexane Cyclopentane Aniline15 0.1259 96 25 0.311 96 A = methylcyclohexane TolueneMethylperfluorooctanoate 10 0.1297 58 25 0.200 58 A = isooctane BenzeneFurfural 25 0.833 44 Cyclohexane Furfural 25 0.1076 44 n-Hexane Furfural30 0.083 78 A = perfluoroheptane Perfluorocyclic oxide Carbontetrachloride 30 0.1370 58 Perfluorocyclic oxide n-Heptane 30 0.329 58 A= perfluoro-n-hexane n-Hexane Benzene 30 6.22 80 n-Hexane Carbondisulfide 25 6.50 80 A = perfluorotri-n-butylamine Iso-octaneNitroethane 25 3.59 119 31.5 2.36 119 33.7 4.56 119 A = toluene AcetoneEthylene glycol 0 0.286 100 24 0.326 100 A = triethylene glycolα-Picotine Methylcyclohexane 20 3.87 14 α-Picotine Diisobutylene 200.445 14 α-Picotine Mixed heptanes 20 0.317 14 A = triolein Oleic acidPropane 85 0.138 40 A = water Acetaldehyde n-Amyl alcohol 18 1.43 74Acetaldehyde Benzene 18 1.119 74 Acetaldehyde Furfural 16 0.007 74Acetaldehyde Toluene 17 0.478 74 Acetaldehyde Vinyl acetate 20 0.560 81Acetic acid Benzene 25 0.0328 43 30 0.0984 38 40 0.1022 38 50 0.0558 3860 0.0637 38 Acetic acid 1-Butanol 26.7 1.613 102 Acetic acid Butylacetate 30 0.705 45 0.391 67 Acetic acid Caproic acid 25 0.349 73 Aceticacid Carbon tetrachloride 27 0.1920 91 27.5 0.0549 54 Acetic acidChloroform ca. 25 0.178 70 25 0.0865 72 56.8 0.1573 17 Acetic acidCreosote oil 34 0.706 91 Acetic acid Cyclohexanol 26.7 1.325 102 Aceticacid Diisobutyl ketone 25-26 0.284 75 Acetic acid Di-n-butyl ketone25-26 0.379 75 Acetic acid Diisopropyl carbinol 25-26 0.800 75 Aceticacid Ethyl acetate 30 0.907 30 Acetic acid 2-Ethylbutyric acid 25 0.32373 Acetic acid 2-Ethylhexnic acid 25 0.286 73 Acetic acid Ethylidenediacetate 25 0.85 104 Acetic acid Ethyl propionate 28 0.510 87 Aceticacid Fenchone 25-26 0.310 75 Acetic acid Furfural 26.7 0.787 102 Aceticacid Heptadecanol 25 0.312 114 50 0.1623 114 Acetic acid 3-Heptanol 250.828 76 Acetic acid Hexane acetate 25-26 0.520 75 Acetic acid Hexane 310.0167 85 Acetic acid Isoamyl acetate 25-26 0.343 75 Acetic acidIsophorone 25-26 0.858 75 Acetic acid Isopropyl ether 20 0.248 31 25-260.429 75 Acetic acid Methyl acetate — 1.273 67 Acetic acid Methylbutyrate 30 0.690 66 Acetic acid Methyl cyclohexanone 25-26 0.930 75Acetic acid Methylisobutyl carbinol 30 1.058 83 Acetic acidMethylisobutyl ketone 25 0.657 97 25-26 0.753 75 Acetic acidMonochlorobenzene 25 0.0435 77 Acetic acid Octyl acetate 25-26 0.1805 75Acetic acid n-Propyl acetate — 0.638 67 Acetic acid Toluene 23 0.0644131 Acetic acid Trichloroethylene 27 0.140 91 30 0.0549 54 Acetic acidVinyl acetate 28 0.294 103 Acetone Amyl acetate 30 1.228 117 AcetoneBenzene 15 0.940 11 30 0.862 11 45 0.725 11 Acetone n-Butyl acetate —1.127 67 Acetone Carbon tetrachloride 30 0.238 12 Acetone Chloroform 251.830 43 25 1.720 3 Acetone Dibutyl ether 25.26 1.941 75 Acetone Diethylether 30 1.00 54 Acetone Ethyl acetate 30 1.500 117 Acetone Ethylbutyrate 30 1.278 117 Acetone Ethyl propionate 30 1.385 117 Acetonen-Heptane 25 0.274 112 Acetone n-Hexane 25 0.343 114 Acetone Methylacetate 30 1.153 117 Acetone Methylisobutyl ketone 25-26 1.910 75Acetone Monochlorobenzene 25-26 1.000 75 Acetone Propyl acetate 30 0.243117 Acetone Tetrachloroethane 25-26 2.37 57 Acetone Tetrachloroethylene30 0.237 88 Acetone 1,1,2-Trichloroethane 25 1.467 113 Acetone Toluene25-26 0.835 75 Acetone Vinyl acetate 20 1.237 81 25 3.63 104 AcetoneXylene 25-26 0.659 75 Allyl alcohol Diallyl ether 22 0.572 32 AnilineBenzene 25 14.40 40 50 15.50 40 Aniline n-Heptane 25 1.425 40 50 2.20 40Aniline Methylcyclohexane 25 2.05 40 50 3.41 40 Aniline Nitrobenzene 2518.69 108 Aniline Toluene 25 12.91 107 Aniline hydrochloride Aniline 250.0540 98 Benzoic acid Methylisobutyl ketone 26.7 76.9* 49 iso-ButanolBenzene 25 0.989 1 iso-Butanol 1,1,2,2-Tetrachloroethane 25 1.80 38iso-Butanol Tetrachloroethylene 25 0.0460 7 n-Butanol Benzene 25 1.263126 35 2.12 126 n-Butanol Toluene 30 1.176 37 tert-Butanol Benzene 250.401 99 tert-Butanol tert-Butyl hypochlorite 0 0.1393 130 20 0.1487 13040 0.200 129 60 0.539 129 tert-Butanol Ethyl acetate 20 1.74 52-Butoxyethanol Methylethyl ketone 25 3.05 68 2,3-Butylene glycoln-Butanol 26 0.597 71 50 0.893 71 2,3-Butylene glycol Butyl acetate 260.0222 71 50 0.0325 71 2,3-Butylene glycol Butylene glycol diacetate 260.1328 71 75 0.565 71 2,3-Butylene glycol Methylvinyl carbinol acetate26 0.237 71 50 0.351 71 75 0.247 71 n-Butylamine Monochlorobenzene 251.391 77 t-Butyraldehyde Ethyl acetate 37.8 41.3 52 Butyric acid Methylbutyrate 30 6.75 66 Butyric acid Methylisobutyl carbinol 30 12.12 83Cobaltous chloride Dioxane 25 0.0052 93 Cupric sulfate n-Butanol 300.000501 9 Cupric sulfate sec-Butanol 30 0.00702 9 Cupric sulfate Mixedpentanols 30 0.000225 9 p-Cresol Methylnaphthalene 35 9.89 62 Diacetonealcohol Ethylbenzene 25 0.335 22 Diacetone alcohol Styrene 25 0.445 22Dichloroacetic acid Monochlorobenzene 25 0.0690 77 1,4-Dioxane Benzene25 1.020 8 Ethanol n-Amyl alcohol 25-28 0.598 75 Ethanol Benzene 250.1191 13 25 0.0536 115 Ethanol n-Butanol 20 3.00 26 Ethanol Cyclohexane25 0.0157 118 Ethanol Cyclohexene 25 0.0244 124 Ethanol Dibutyl ether25-26 0.1458 75 Ethanol Di-n-propyl ketone 25-26 0.592 75 Ethanol Ethylacetate 0 0.0263 5 20 0.500 5 70 0.455 41 Ethanol Ethyl isovalerate 250.392 13 Ethanol Heptadecanol 25 0.270 114 Ethanol n-Heptane 30 0.274 94Ethanol 3-Heptanol 25 0.783 76 Ethanol n-Hexane 25 0.00212 111 Ethanoln-Hexanol 28 1.00 56 Ethanol sec-Octanol 28 0.825 56 Ethanol Toluene 250.01816 122 Ethanol Trichloroethylene 25 0.0662 16 Ethylene glycoln-Amyl alcohol 20 0.1159 59 Ethylene glycol n-Butanol 27 0.412 85Ethylene glycol Furfural 25 0.315 18 Ethylene glycol n-Hexanol 20 0.27559 Ethylene glycol Methylethyl ketone 30 0.0527 85 Formic acidChloroform 25 0.00445 72 50.9 0.0192 17 Formic acid Methylisobutylcarbinol 30 1.218 83 Furfural n-Butane 51.5 0.712 42 79.5 0.930 42Furfural Methylisobutyl ketone 25 7.10 19 Furfural Toluene 25 5.64 53Hydrogen chloride iso-Amyl alcohol 25 0.170 21 Hydrogen chloride2,6-Dimethyl-4-heptanol 25 0.266 21 Hydrogen chloride 2-Ethyl-1-butanol25 0.534 21 Hydrogen chloride Ethylbutyl ketone 25 0.01515 79 Hydrogenchloride 3-Heptanol 25 0.0250 21 Hydrogen chloride 1-Hexanol 25 0.345 21Hydrogen chloride 2-Methyl-1-butanol 25 0.470 21 Hydrogen chlorideMethylisobutyl ketone 25 0.0273 70 Hydrogen chloride 2-Methyl-1-pentanol25 0.502 21 Hydrogen chloride 2-Methyl-2-pentanol 25 0.411 21 Hydrogenchloride Methylisopropyl ketone 25 0.0814 79 Hydrogen chloride 1-Octanol25 0.424 21 Hydrogen chloride 2-Octanol 25 0.380 21 Hydrogen chloride1-Pentanol 25 0.257 21 Hydrogen chloride Pentanols (mixed) 25 0.271 21Hydrogen Buoride Methylisobutyl ketone 25 0.370 79 Lactic acid iso-Amylalcohol 25 0.352 128 Methanol Benzene 25 0.01022 4 Methanol n-Butanol 00.600 65 15 0.479 65 30 0.510 65 45 1.260 65 60 0.682 65 Methanolp-Cresol 35 0.313 82 Methanol Cyclohexane 25 0.0150 125 MethanolCyclohexane 25 0.01043 124 Methanol Ethyl acetate 0 0.0589 5 20 0.238 5Methanol n-Hexanol 28 0.585 55 Methanol Methylnaphthalene 25 0.025 82 350.0223 82 Methanol sec-Octanol 28 0.584 55 Methanol Phenol 25 1.333 82Methanol Toluene 25 0.0099 60 Methanol Trichloroethylene 27.5 0.0167 54Methyl-n-butyl ketone n-Butanol 37.8 53.4 52 Methylethyl ketoneCyclohexane 25 1.775 48 30 3.60 85 Methylethyl ketone Casoline 25 1.68664 Methylethyl ketone n-Heptane 25 1.548 112 Methylethyl ketone n-Hexane25 1.775 112 37.8 2.22 52 Methylethyl ketone 2-Methyl furan 25 84.0 109Methylethyl ketone Monochlorobenzene 25 2.36 68 Methylethyl ketoneNaphtha 28.7 0.885† 6 Methylethyl ketone 1,1,2-Trichloroethane 25 3.4468 Methylethyl ketone Trichloroethylene 25 3.87 68 Methylethyl ketone2,2,4-Trimethylpentane 25 1.572 64 Nickelous chloride Dioxane 25 0.001793 Nicotine Carbon tetrachloride 25 9.50 34 Phenol Methylnaphthalene 237.00 82 a-Picoline Benzene 20 8.75 14 a-Picoline Diisobutylene 20 1.36014 a-Picoline Heptanes (mixed) 20 1.378 14 a-Picoline Methylcylohoxane20 1.00 14 iso-Propanol Benzene 25 0.276 69 iso-Propanol Carbontetrachloride 20 1.405 25 iso-Propanol Cyclohexane 25 0.0282 123iso-Propanol Cyclohexane 15 0.0583 124 25 0.0682 124 35 0.1875 124iso-Propanol Diisopropyl ether 25 0.406 35 iso-Propanol Ethyl acetate 00.200 5 20 1.205 5 iso-Propanol Tetrachloroethylene 25 0.388 7iso-Propanol Toluene 25 0.1296 121 n-Propanol iso-Amyl alcohol 25 3.3420 n-Propanol Benzene 37.8 0.650 61 n-Propanol n-Butanol 37.8 3.61 61n-Propanol Cyclohexane 25 0.1553 123 35 0.1775 123 n-Propanol Ethylacetate 0 1.419 5 20 1.542 5 n-Propanol n-Heptane 37.8 0.540 61n-Propanol n-Hexane 37.8 0.320 61 n-Propanol n-Propyl acetate 20 1.55106 35 2.14 106 n-Propanol Toluene 25 0.299 2 Propionic acid Benzene 300.598 57 Propionic acid Cyclohexane 31 0.1955 84 Propionic acidCyclohexene 31 0.303 84 Propionic acid Ethyl acetate 30 2.77 87Propionic acid Ethyl butyrate 26 1.470 87 Propionic acid Ethylpropionate 28 0.510 87 Propionic acid Hexane (mixed) 31 0.186 84Propionic acid Methyl butyrate 30 2.15 68 Propionic acid Methylisobutylcarbinol 30 3.52 83 Propionic acid Methylisobutyl ketone 26.7 1.949* 49Propionic acid Monochlorobenzene 30 0.513 57 Propionic acidTetrachloroethylene 31 0.167 84 Propionic acid Toluene 31 0.515 84Propionic acid Trichloroethylene 30 0.496 57 Pyridine Benzene 15 2.19110 25 3.00 105 25 2.73 120 45 2.49 110 60 2.10 110 PyridineMonochlorobenzene 25 2.10 77 Pyridine Toluene 25 1.900 120 PyridineXylene 25 1.260 120 Sodium chloride iso-Butanol 25 0.0182 36 Sodiumchloride n-Ethyl-sec-butyl amine 32 0.0583 24 Sodium chloriden-Ethyl-tert-butyl amine 40 0.1792 24 Sodium chloride 2-Ethylhexyl amine30 0.187 24 Sodium chloride 1-Methyldiethyl amine 39.1 0.0597 24 Sodiumchloride 1-Methyldodecyl amine 30 0.693 24 Sodium chloriden-Methyl-1,3-dimethylbutyl amine 30 0.0537 24 Sodium chloride1-Methyloctyl amine 30 0.589 24 Sodium chloride tert-Nonyl amine 300.0318 24 Sodium chloride 1,1,3,3-Tetramethyl butyl amine 30 0.072 24Sodium hydroxide iso-Butanol 25 0.00857 36 Sodium nitrate Dioxane 250.0246 95 Succinic acid Ethyl ether 15 0.220 33 20 0.193 33 25 0.1805 33Trimethyl amine Benzene 25 0.857 51 70 2.36 51 *Concentrations inlb.-moles/cu. ft. †Concentrations in volume fraction.

While in accordance with the patent statutes the best mode and preferredembodiment have been set forth, the scope of the invention is notintended to be limited thereto, but only by the scope of the attachedclaims.

What is claimed is:
 1. A filter for removing an immiscible lipophilicliquid or a hydrophilic liquid respectively from a continuoushydrophilic liquid phase or a continuous lipophilic liquid phase,comprising: a mixture of a plurality of hydrophobic fibers and aplurality of hydrophilic fibers, each of said fibers having a fiberdiameter, wherein the fiber diameters of the hydrophobic fibers and thehydrophilic fibers are substantially similar, said hydrophilic fibershaving a wetting value and said hydrophobic fibers having a differentwetting value within a liquid system comprising the immisciblelipophilic liquid or the immiscible hydrophilic liquid and respectivelythe continuous hydrophilic liquid phase or the continuous lipophiliccontinuous liquid phase, said hydrophobic fibers and hydrophilic fibersforming pores within the filter, each of said pores having a pore size,where the pore sizes are substantially similar; the amount of saidhydrophobic fibers to said hydrophilic fibers being within a range offrom about 80% to about 20% by weight with the remaining weight percentbeing said hydrophilic fibers and said fiber weight ratio amount beingan effective amount to coalesce an immiscible liquid within a continuousliquid phase; and wherein the filter has a predetermined L/H ratio suchthat the filter is thereby capable of removing an immiscible liquid froma continuous liquid phase.
 2. The filter of claim 1, wherein said filterhas an L/H ratio of from about 2 to about 2,000.
 3. The filter of claim2, wherein said filter has an L/H ratio of from about 2 to about 200,wherein the weight ratio of said hydrophobic fibers to said hydrophilicfibers is from about 70% to about 30% by weight, and wherein saidhydrophobic and said hydrophilic fibers, independently, have a fiberdiameter of from about 0.1 to about 500 microns.
 4. The filter of claim3, wherein said L/H ratio is from about 2 to about 150, and wherein saidfiber diameter of said hydrophobic fibers and hydrophilic fibers,independently, is from about 1 to about 10 microns.
 5. The filter ofclaim 4, wherein said hydrophobic fibers include polyethylene,polypropylene, or polyester, and halogen-containing fibers, and whereinsaid hydrophilic fibers comprise glass fibers.
 6. The filter of claim 1,wherein said hydrophobic fibers include polymers comprise one or morepolymers including polyethylene, polypropylene, nomex, polyester, ahalogen-containing polymer, rubber, polyurethane, polycarbonate, or asilicone polymer; one or more minerals such as zinc oxide; and fibersthat contain silane coatings thereon; and wherein said hydrophilicfibers comprise one or more glasses including sodium glass, boron glass,phosphate glass, or 8-glass; one or more minerals including alumina,titania, or silica; one or more metals including aluminum or aluminumalloys; and one or more polymers including cellulose acetate,poly(methylmethacrylate), polyethylene oxide, or nylon.